Hello...my wife is 36 years old, 5 6 , 125 lbs., fit and athletic...while jogging/running on our treadmill, her heartrate will jump from 175/180 BPM to 210/215 BPM for a short period of time (maybe a minute or so) without changing her output (i.e. running pace)...I m confident the heartrate monitor is correct because it works fine on me. The BPM when I m using the treadmill monitor are consistent with a different heartrate monotor I use on a street bike. In addition to her heartrate spikes, I personally think her jogging BPM rate is not consistent (too high) relative to output. Do you see any of this to be a problem?